[Git][NTPsec/ntpsec][master] 2 commits: ntpfrob: remove obsolete comment about struct timeval.

[Gary E. Miller]

Gary E. Miller pushed to branch master at NTPsec / ntpsec


Commits:
70c6b6cd by Gary E. Miller at 2016-11-14T17:48:43-08:00
ntpfrob: remove obsolete comment about struct timeval.

- - - - -
321a13a7 by Gary E. Miller at 2016-11-14T17:58:33-08:00
ntpfrob: stop assuming pre-2000 CPu speeds.

clock resolutions under 5 microSec are now common.

- - - - -


1 changed file:

- ntpfrob/precision.c


Changes:

=====================================
ntpfrob/precision.c
=====================================
--- a/ntpfrob/precision.c
+++ b/ntpfrob/precision.c
@@ -31,9 +31,6 @@ void precision(const iomode mode)
 /* Find the resolution of the system clock by watching how the current time
  * changes as we read it repeatedly.
  *
- * struct timeval is only good to 1us, which may cause problems as machines
- * get faster, but until then the logic goes:
- *
  * If a machine has resolution (i.e. accurate timing info) > 1us, then it will
  * probably use the "unused" low order bits as a counter (to force time to be
  * a strictly increaing variable), incrementing it each time any process
@@ -61,12 +58,12 @@ void precision(const iomode mode)
 
 #define	DNSECS	1000000000L
 #define	HUSECS	(1024 * 1024)
-#define	MINSTEP	5000	/* some systems increment uS on each call */
-/* Don't use "1" as some *other* process may read too*/
-/*We assume no system actually *ANSWERS* in this time*/
+#define	MINSTEP	200	/* assume no system returns less than 200 nansec */
+/* Don't use "1" as some *other* process may read too */
+/* We assume no system actually *ANSWERS* in this time */
 #define MAXSTEP 20000000   /* maximum clock increment (ns) */
 #define MINLOOPS 5      /* minimum number of step samples */
-#define	MAXLOOPS HUSECS	/* Assume precision < .1s ! */
+#define	MAXLOOPS (HUSECS * 1024)	/* Assume precision < .1s ! */
 
 int
 default_get_resolution(void)
@@ -94,15 +91,15 @@ default_get_resolution(void)
 
 	diff = (diff *3)/2;
 	if (i >= MAXLOOPS) {
-		fprintf(stderr,
-			"     (Boy this machine is fast ! %d loops without a step)\n",
-			MAXLOOPS);
-		diff = 1; /* No STEP, so FAST machine */
+	    fprintf(stderr,
+		"     (Boy this machine is fast ! %d loops without a step)\n",
+		MAXLOOPS);
+	    diff = 1; /* No STEP, so FAST machine */
 	}
 	if (i == 0) {
-		fprintf(stderr,
-			"     (The resolution is less than the time to read the clock -- Assume 1us)\n");
-		diff = 1; /* time to read clock >= resolution */
+	    fprintf(stderr,
+		"     (The resolution is less than the time to read the clock -- Assume 1us)\n");
+	    diff = 1; /* time to read clock >= resolution */
 	}
 	for (i=0, val=HUSECS; val>0; i--, val >>= 1) if (diff >= val) return i;
 	fprintf(stderr,



View it on GitLab: https://gitlab.com/NTPsec/ntpsec/compare/6209d81be9c86c8ff82c042f97561c5f8d439c5e...321a13a7e2d1f7e936857a2e6f0cc39a04b17a08
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